#include <stdio.h>
#include <string.h>
#include <assert.h>
#include "zlib.h"

#if defined(MSDOS) || defined(OS2) || defined(WIN32) || defined(__CYGWIN__)
#  include <fcntl.h>
#  include <io.h>
#  define SET_BINARY_MODE(file) setmode(fileno(file), O_BINARY)
#else
#  define SET_BINARY_MODE(file)
#endif

/* Tamanho do buffer usado para passar dados para as rotinas */
#define CHUNK 16384


/*The zlib format has a very small header of only two bytes to identify it as a zlib stream and to provide decoding information, and a four-byte trailer    with a fast check value to verify the integrity of the uncompressed data after decoding.*/


/* report a zlib or i/o error */
void zerr(int ret)
{
    fputs("zpipe: ", stderr);
    switch (ret) {
    case Z_ERRNO:
        if (ferror(stdin))
            fputs("error reading stdin\n", stderr);
        if (ferror(stdout))
            fputs("error writing stdout\n", stderr);
        break;
    case Z_STREAM_ERROR:
        fputs("invalid compression level\n", stderr);
        break;
    case Z_DATA_ERROR:
        fputs("invalid or incomplete deflate data\n", stderr);
        break;
    case Z_MEM_ERROR:
        fputs("out of memory\n", stderr);
        break;
    case Z_VERSION_ERROR:
        fputs("zlib version mismatch!\n", stderr);
    }
}


/* compress or decompress from stdin to stdout */
int main(int argc, char **argv)
{
    int ret;
    FILE *in, *out;

    in = fopen(argv[1], "r");
    out = fopen(argv[2], "w");

    /* avoid end-of-line conversions */
    SET_BINARY_MODE(in);
    SET_BINARY_MODE(out);

    /* do compression if no arguments */
    if (argc == 3) {
        ret = def(in, out, Z_DEFAULT_COMPRESSION);
        if (ret != Z_OK)
            zerr(ret);
        fclose(in);
        fclose(out);
        return ret;
    }

    /* otherwise, report usage */
    else {
        fputs("zpipe usage: zpipe [-d]  source  dest\n", stderr);
        return 1;
    }
}


/* Compress from file source to file dest until EOF on source.
   def() returns Z_OK on success, Z_MEM_ERROR if memory could not be
   allocated for processing, Z_STREAM_ERROR if an invalid compression
   level is supplied, Z_VERSION_ERROR if the version of zlib.h and the
   version of the library linked do not match, or Z_ERRNO if there is
   an error reading or writing the files. */
int def(FILE *source, FILE *dest, int level)
{
    int ret, flush;  /*ret will be used for zlib return codes and flush will keep track of the current flushing state for deflate()*/
    unsigned have; /*have is the amount of data returned from deflate()*/
    z_stream strm; /*strm structure is used to pass information to and from the zlib routines*/
    unsigned char in[CHUNK];  /*in is the input buffer for deflate().*/
    unsigned char out[CHUNK];  /*out is the output buffer for deflate().*/

    /* allocate deflate state */
    strm.zalloc = Z_NULL;
    strm.zfree = Z_NULL;
    strm.opaque = Z_NULL;
    ret = deflateInit(&strm, level);
    if (ret != Z_OK)
        return ret;

    /* compress until end of file */
    do {
        strm.avail_in = fread(in, 1, CHUNK, source);

        if (ferror(source)) {
            (void)deflateEnd(&strm);
            return Z_ERRNO;
        }

        flush = feof(source) ? Z_FINISH : Z_NO_FLUSH;
        strm.next_in = in;

	/* run deflate() on input until output buffer not full, finish
           compression if all of source has been read in */
        do {
	    strm.avail_out = CHUNK;
            strm.next_out = out;

	    ret = deflate(&strm, flush);    /* no bad return value */
            assert(ret != Z_STREAM_ERROR);  /* state not clobbered */

	    have = CHUNK - strm.avail_out; /* how much output deflate() provided on the last call: (space provided before the call) - (output space 																available after the call) */

            if (fwrite(out, 1, have, dest) != have || ferror(dest)) {
                (void)deflateEnd(&strm);
                return Z_ERRNO;
            }

    	} while (strm.avail_out == 0); /* check if all input was used */
    	assert(strm.avail_in == 0);     /* all input will be used */

    /* done when last data in file processed */
    } while (flush != Z_FINISH);
    assert(ret == Z_STREAM_END);        /* stream will be complete */

    printf("\nhave: %d\n", have);
        
    /* clean up and return */
    (void)deflateEnd(&strm);
    return Z_OK;
}

